81534920 has 16 divisors (see below), whose sum is σ = 183453660. Its totient is φ = 32613952.

The previous prime is 81534919. The next prime is 81534949. The reversal of 81534920 is 2943518.

It can be written as a sum of positive squares in 2 ways, for example, as 73994404 + 7540516 = 8602^2 + 2746^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1019147 + ... + 1019226.

Almost surely, 2^81534920 is an apocalyptic number.

It is an amenable number.

81534920 is an abundant number, since it is smaller than the sum of its proper divisors (101918740).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81534920 is a wasteful number, since it uses less digits than its factorization.

81534920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2038384 (or 2038380 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 32.

The square root of 81534920 is about 9029.6688754350. The cubic root of 81534920 is about 433.6252365907.

The spelling of 81534920 in words is "eighty-one million, five hundred thirty-four thousand, nine hundred twenty".